GB2108352A

GB2108352A - Copying cinematographic film onto colour video tape

Info

Publication number: GB2108352A
Application number: GB08223255A
Authority: GB
Inventors: Tomas Dyfverman
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-08-21
Filing date: 1982-08-12
Publication date: 1983-05-11
Also published as: SE8104965L; SE427608B; DE3230801A1; US4496990A; GB2108352B

Description

1 GB 2 108 352 A 1

SPECIFICATION

A method of and apparatus for copying cinematographic film onto colour video tape In the copying or transfer of cinematographic film onto colou r video ta pe, the fi I m is passed th roug h telecine equipment which sequentially scans the picture frames of the film and generates an electro- nic picture signal containing picture information relating to the film picture frames. This picture signal, which in reality mostly consists of three signals for the three colours red, green and blue, and which is consequently sometimes referred to as the RGB-signal or colour video signal in component form, is then coded in accordance with the colour video system used, so as to obtain a complete video signal, which is recorded onto video tape by means of a video tape recorder. A result of this coding is that the complete colour video signal will include one or more periodic signal components having a period extending over a section of the picture signal corresponding to an integral number of picture frames on the film.

In the case of the so-called PAL colour video 90 system, for example, each picture frame on the film is scanned by the telecine equipment twice, each scan deriving half the picture content of said picture frame, so that the picture signal, and thus also the coded complete video signal, will include two mutually sequential sections for each film frame, these sections being referred to hereinafter as video fields, which together contain the total picture information of the film frame in question. In the PAL system, coding of the picture signal will also mean thatthe complete video signal will include a first periodic signal component whose period corresponds to two film frames, i.e. four mutually sequential video fields. There is also present a second periodic signal component, whose period duration corresponds to four film frames, i.e. eight video fields. These two periodic signal components have a fixed mutual phase relationship. The relationship is that illustrated schematically in Fig. 1 of the accom- panying drawings, this figure illustrating schematically a video tape V having eight mutually sequential video fields, which are referenced V1 48 and which are assumed to lie within the period of the periodic signal component of the complete video signal which extends over eight video fields and which thus 115 covers two mutually sequential periods of the periodic signal component in the video signal covering four video fields. For the sake of simplicity, these periodic signal components will also sometimes be referred to as the field sequence of the video signal. 120

Fig. 1 also illustrates schematically a section of a film F with four mutually sequential picture frames R-M, which in the illustrated, example are assumed to have correspondence with the video fields V1 48 on the video tape. If the video tape copied from the film is to be used for editing purposes and/or be usable for still-frame viewing by means of a playback device, for example a video tape recorder, which in its stillframe viewing mode shows two mutually sequential video fields, it is essential that when copying the film onto the video tape a specific mutual phase relationship can be obtained between the film frames, i.e. the picture content of the video signal, and the said field sequence of said videosig- nal. It is of primary importance that either the first two video fields V1 and V2 in the field sequence V1 -V8 originate from one and the same picture frame of the film, which automatically means, of course, that the video fields V3X4 also stem from one and the same picture frame, and likewise the video fields V5, V6 and V7, V8, or alternatively that the video fields V2 and V3 originate from the same film picture frame, it being understood that in this case the video fields V4, V5 and V6, V7 and V8 together with V1 of the next following video field sequence, respectively, also originate from their respective film picture frames. When copying film onto video tape, it must be possible to differentiate between these two possible alternatives and to determine beforehand which one is applicable, since certain video-tape editing apparatus and video tape recorders with still-frame viewing are found which, in order to function correctly, require the application of one of the said alternatives, while other editing apparatus and video tape recorders require application of the other alternative. Hereinafter, the first mentioned alternative is referred to as alternative A while the other alternative is referred to as afternative B. It is also important in some cases, when copying film onto video tape, to ensure that a given film picture frame will have correspondence with two video fields which occupy a given predetermined position within the periodic field sequence covering eight video fields V1 -V8, or at least within the periodic field sequence covering four mutually sequential video fields. Thus, for example, it may be desired to prescribe that film picture frame F2 in Fig. 1 has correspondence with video fields located at positions V3 and V4 in the field sequence covering eight video fields on the video tape, or at least that said picture frame has correspondence in two video fields located in either position V3, V4 or V7, V8, i.e. located at a certain given position within the field sequence on the video tape covering four video fields.

Some, although not all, forms of apparatus, used at present to copy film onto video tape are able to differentiate between these two alternatives A and B, and to determine which alternative is applicable in a particular case. It is not possible, however, with any of the known forms of copying apparatus to determine beforehand where specific film picture frames will be located in the field sequences of the colour video signals covering four or eight picture fields respectively. In the case of known copying apparatus, the coding unit used to code the picture signal in component form, in accordance with the colour video system used, operates continuously at a predetermined speed, while the picture signal containing the picture information of the film frames is not obtained until the film feeding mechanism of the telecine equipment has been started and reached its prescribed speed. The phase relationship between the picture signal and the coding is consequently 2 quite random.

Accordingly, it is among the objects of the present invention to provide a method of, and corresponding apparatus for, copying film onto colour video tape and by means of which there can be obtained a predetermined, desired mutual phase relationship between the picture frames of the film and the periodic field sequence of the video tape.

According to one aspect of the invention there is provided a method of copying cinematographic film onto colour video tape, in which the picture frames of the film are scanned electronically in sequence by means of telecine equipment in which an electronic picture signal containing the picture information of the film picture frames is generated and said picture 80 signal is coded in accordance with the colour video system used so as to provide a composite video signal which includes at least one periodic signal component having a period extending over an integral number of film picture frames, and in which 85 said composite video signal is recorded onto a video tape, wherein there is spliced onto one end of the film a film leader provided with a periodically repeated sequence of at leasttwo mutually sequen tial picture frames each having a picture content which is clearly different from the other, and where in said leader is spliced to said film in such a way that said picture frame sequence has a predeter mined position relative to the picture frames on the actual film; and wherein the film is fed onto the telecine equipment with said film leader entering first; and, while the leader is fed through the telecine equipment, the picture content of said picture signal is compared with said periodic signal component in order to establish whether or not the picture content 100 of the picture signal has a given desired phase relationship with said periodic signal component before copying of the actual film onto the video tape commences.

According to another aspect of this invention there 105 is provided an apparatus for copying cinematographic film onto colour video tape, comprising telecine equipment arranged to scan electronically the picture frames of the film in sequence, and to generate an electronic picture signal containing the picture information of the film picture frames; means for coding said picture signal in accordance with the colour video system used so as to provide a composite video signal which includes at least one periodical signal component characteristic of the colour video system in question; and a tape recording means for recording said composite video signal on a video tape, wherein said apparatus also includes means for detecting, when feeding through the telecine equipment a film leader containing a periodically repeated sequence of at least two mutually sequential picture frames having picture contents which clearly differ one from the other, the current picture content of said picture signal at any given time and for generating a signal representative of the various picture frames in said picture frame sequence; and means for comparing said signal with said periodic signal components of the composite video signal and for indicating whether or not said picture frame sequence has a desired phase rela- GB 2 108 352 A 2 tionship with said periodic signal component.

Embodiments of the invention are described below, by way of example, with reference to the accompanying drawings, in which Figure 1 is the previously referred to schematic illustration showing the relationship between the picture frames of a cine film and the video fields of a corresponding recording on video tape;

Figure 2 illustrates schematically by way of exam- ple a first embodiment of a film leader which, in a method embodying the invention, is spliced on to one end of a film priorto copying the film onto video tape; Figure 3A illustrates an example of a truth table for a logic unit incorporated in apparatus embodying the invention when using the film leader according to Figure 2; Figure 4A illustrates an example of another truth table for the logic unit incorporated in the apparatus embodying the invention when using a film leader according to Figure 2; Figures 3B and 4B illustrate respectively truth tables corresponding to those illustrated in Figures 3A and 4A but intended for copying work carried out in accordance with alternative B; Figure 5 illustrates schematically, byway of example, a second embodiment of a film leader which, in a method embodying the invention, is spliced to one end of the film to be copied; Figure 6 illustrates by way of example a truth table for the logic unit incorporated in the apparatus embodying the invention when using a film leader according to Figure 5; and Figure 7 illustrates schematically an example of copying apparatus embodying the invention.

As illustrated schematically in Figure 7, telecine equipment for copying cinematographic colour film onto colour film onto colour video tape comprises in principle a so-called film scanner 1 which is provided with means for feeding a film F there-through and in which the picture frames of the film are scanned electronically in sequence and an electronic picture signal, RGB-signal or video signal in component form, containing the picture information of said picture frames is generated in the manner previously described. The picture signal is transmitted from the scanner 1 to a coding unit 2, in which the picture signal from the scanner 1 is coded in accordance with the colour video system used, so as to obtain from the coding unit 2 a complete video signal having the aforementioned periodic field sequences, this signal being transmitted to a video tape recorder 4, which records the video signal on a video tape V.

When practising the method according to the invention there is spliced onto one end of the film to be copied a leader provided with a periodically repeated sequence of mutually sequential picture frames whose picture contents clearly differ one from the other.

An embodiment of this method is illustrated schematically in Figure 2, which shows one end of the actual film F and part of a film leader FS spliced to one end of the film. In the illustrated emodiment, the leader FS is provided with a periodically repe- ated sequence of two picture frames FS1 and FS2 z 3 GB 2 108 352 A 3 having markedly different picture contents, in that the picture frame FS1 of the illustrated emodiment is dark, for example black, while the picture frame FS2 is light, for example white.

The film F on which the leader FS has been spliced is loaded into the scanner 1 in such a way that the leader FS is scanned first. During the scanning of the leader it is continuously determined whether the electronic picture signal from the scanner 1 origin- ates from a dark picture frame FS1 or alight picture frame FS2 on the leader FS, and a signal representating the current picture content of the picture signal is generated and sent to a logic comparison circuit 5. As illustrated in Figure 7, this can either be effected by sending the picture signal from the scanner 1 to the comparison circuit 5 and electronically analysing the signal therein, or by transmitting the complete video signal from the coder 2 to a TV-monitor 6 having mounted on the screen thereof photo detec- tors 7 arranged to sense the nature of the current image and to send corresponding signals to the logic comparison circuit 5. This circuit 5 is also arranged to receive information from the coder 2 concerning the position of the current video field in the eriodic sequence of video fields V1 X8.

The logic comparison circuit 5 is of conventional design and is arranged to compare the phase relationship between the field sequence V1 X8 and the picture frame sequence FS1, FS2 by determining whether certain given video fields in the sequence V1-VI3 occur simultaneously with certain, given picture frames in the picture frame sequence FS1, FS2 in accordance with a predetermined logic truth table. A truth table which can be used in the present context is illustrated in Figure 3A. It should be noted that in the case of a film leader containing a periodically repeated picture frame sequence which only includes two mutually sequential picture frames, as shown in Figure 2 for example, attention can only be paid to the periodic field seqence of the video signal extending over four mutually sequential video fields, i.e. overtwo mutually sequential picture frames, and hence the video fields V1 and V5 in Figure 1 are to be considered as being similarly located in the field sequence, which thus also applies to the video fields V2, V6 and similarly video fields V3, V7 and video fields V4, V8. According to the truth table illustrated by way of example in Figure 3A the only phase relationship which the logic comparison circuit 5 will accept as being correct is when the picture frames ES1 on the leader FS appear simultaneously with video fields V1N5 and V2/V6, while the picture frames FS2 appear simultaneously with video fields V3N5 and V2/V6, while the picture frames FS2 appear simultaneously with video fields V3N7 and V4/V8. This is one of the four different possible mutual phase relationships between the video field sequence and the picture frame sequence, and the only one which ensures that a picture frame FS1 always has correspondence in the video fields V1/V5 and V2/V6 in the field sequence, while a picture frame FS2 always has correspondence in the video fields V3N7 and V4N8 in the field sequence. When the film leader FS and the actual film F are spliced in the manner illustrated schematically in Figure 2, this will mean that an equivalent of the first picture frame of the actual film F will be found in the video fields V1/V5 and V2/V6 in the field sequence. Should any other relationship occur between the video fields and the picture frames, the logic comparison circuit 5 will indicate that the phase relationship between the video fields sequence and the picture frames of the film is wrong. When this occurs, feeding of the film through the scanner 1 is stopped, either manually or by an operator or, as indicated schematically in Figure 7, automatically by means of a signal from the comparison circuit 5. Feeding of the film is then re-started and the logic comparison circuit 5 again compares the mutual phase relationship between the video field sequence and the picture frames and decides whether the phase relationship is this time the desired phase relationship. Since there are only four possible phase relationships and since one of these possible phase relationships is the desired phase relationship, it is highly probably that stopping and re-sta rting need only take place a few times before obtaining the correct desired phase relationship and before copying of the actual film F can take place.

Alternatively, it is possible with the use of control circuits for the film feeding mechanism in the scanner 1 to automatically guide the film to the correct position under the influence of a control signal from the logic comparison circuit 5.

If, when applying the embodiment illustrated in Figure 2, it is instead desired that the first picture frame on the actual film F has correspondence in the video fields V3/V7 and V4/V8 in the video field sequence, the logic comparison circuit 5 is designed to use the truth table shown in Figure 4A instead.

If the location of a given picture frame of the film in the video field sequence is unimportant, and if it is only desired to ensure that the first two video fields V1/V5 and V2/V6 in the video field sequence originate from one and the same picture frame, the logic comparison circuit 5 is designed to accept both the truth table illustrated in Figure 3A and the truth table illustrated in Figure 4A. Thus, in this case, two of the total of four different possible phase relationships between the video field sequence and the picture frames of the film are acceptable for copying of the film. This particular case is of interest when copying film onto black and white video tape, since the black and white video signal has none of the field sequ- ences extending over four or eight video fields respectively, but on the other hand still has a field sequence which extends overtwo video fields, since also in this case each film picture frame has corresponding thereto, two mutually sequential video fields.

It will be understood that the truth tables 3A and 4A enable copying to be carried out in accordance with the aforedescribed alternative A. Corresponding truth tables which enable film to be copied onto video tape in accordance with alternative B will have the form illustrated in Figures 3B and 4B respectively.

If, when copying, it is desired to also take into account the periodic field sequence of the complete video signal covering eight video fields and to

4 ensure that a certain, given film frame in the film, for example the ffirst film frame, takes a given, predetermined position in the field sequence V1 -V8 comprising eight mutually sequential video fields, it is possible to use, for example, a film leader of the form illustrated schematically in Figure 5. This leader is provided with a periodically repeated sequence of four mutually sequential picture frames FS1-FS4 having mutually different, readily discernible picture contents. In this case, the logic comparison circuit 5 may be designed to work, for example, with a truth table according to Figure 6, it being ensured in this waythat a picture frame FS1 on the leader FS, and thus also the first picture frame on the actual film F, will have correspondence in the video fields V1 and V2 of the field sequence V1 -V8. As will be readily understood, this also results in copying according to alternative A.

It will also be understood that the logic compari- son circuit 5 can be designed in a manner which enables it to be switched between various types of truth tables, so as to make it possible to select freely the desired position for a given picture frame of the film, for example the first picture frame, in the field sequence of the video signal.

Although the invention has been described in the afore-going with reference to the PAL system, it will be understood that the invention can also be applied to other colour video systems where the video signal

Claims

includes a periodic signal component having a period which extends over a plurality of mutually sequential picture frames. CLAIMS

1. A method of copying cinematographic film onto colour video tape, in which the picture frames of the film are scanned electronically in sequence by means of telecine equipment in which an electronic picture signal containing the picture information of the film picture frames is generated and said picture signal is coded in accordance with the colour video system used so as to provide a composite video signal which includes at least one periodic signal component having a period extending over an integral number of film picture frames, and in which said composite video signal is recorded onto a video 110 tape, wherein there is spliced onto one end of the film a film leader provided with a periodically repeated sequence of at least two mutually sequential picture frames each having a picture content which is clearly different from the other, and wherein said leader is spliced to said film in such a way that said picture frame sequence has a predetermined position relative to the picture frames on the actual film; and wherein the film is fed onto the telecine equipment with said film leader entering first; and, while the leader is fed through the telecine equipment, the picture content of said picture signal is compared with said periodic signal component in order to establish whether or notthe picture content of the picture signal has a given desired phase relationship with said periodic signal component before copying of the actual film onto the video tape commences.

2. A method according to claim 1, in which said picture frame sequence on the film leader consists of 130 GB 2 108 352 A 4 two mutually sequential picture frames.

3. A method according to claim 1, in which said picture frame sequence on the film leader consists of lour mutually sequential picture frames.

4. A method according to anyone of claims 1-3, in which the various picture frames in said picture frame sequence on the film leader have mutually different, mutually readily discernible combinations of dark portions and light portions.

5. A method according to anyone of claims 1-4, in which the current picture content of the picture signal, while feeding the film leaderthrough the telecine equipment, is established by electronically analysing the electronic picture signal.

6. A method according to any one of claims 1-4, in which the current picture content of the picture signal, while feeding the film leader through the telecine equipment, is established by transmitting the video signal to a TV-monitor and detecting the current image produced on the screen of said monitor by means of photo- detectors.

7. An apparatus for copying cinematographic film onto colour video tape, comprising telecine equipment arranged to scan electronically the picture frames of the film in sequence, and to generate an electronic picture signal containing the picture information of the film picture frames; means for coding said picture signal in accordance with the colour video system used so as to provide a composite video signal which includes at least one periodical signal component characteristic of the colour video system in question; and a tape recording means for recording said composite video signal on a video tape, wherein said apparatus also includes means for detecting, when feeding through the telecine equipment a film leader containing a periodically repeated sequence of at least two mutually sequential picture frames having picture contents which clearly differ one from the other, the current picture content of said picture signal at any given time and for generating a signal representative of the various picture frames in said picture frame sequence; and means for comparing said signal with said periodic signal components of the composite video signal and for indicating whether or not said picture frame sequence has a desired phase relationship with said periodic signal component.

8. Apparatus according to claim 7, in which said means for generating the signal representing the picture frames in said picture frame sequence includes means for electronically analysing the electronic picture signal.

9. Apparatus according to claim 7, in which said means for generating the signal representing the picture frames in said picture frame sequence includes a TV-monitor, to which said composite video signal is transmitted, and photo-detector means arranged to detect the image produced on the screen of said TV- monitor.

10. Apparatus according to anyone of claims 7-9, which includes means influenced by said comparison means and arranged to stop and re-start feeding of film through the telecine equipment, until such time as said desired phase relationship is obtained.

11. A method for copying cinematograph film t GB 2 108 352 A 5 onto colour video tape, substantially as hereinbefore described with reference to Figures 2 to 4B of the accompanying drawings.

12. A method for copying cinematographic film onto colour video tape, substantially as hereinbefore described with reference to Figures 5 and 6 of the accompanying drawings.

13. Apparatus for copying cinematographic film onto colour video tape, substantially as hereinbefore described with reference to and as shown in Figure 7 of the accompanying drawings.

14. Any novel feature or combination of features described herein.

Printed for Her Majesty's Stationery Office by The Tweeddale Press Ltd., Berwick-upon-Tweed, 1983. Published atthe Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.